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Start-ups fuel boom in small-scale nuclear power

A new wave of nuclear scientists aim​s to build small-scale reactors that provide carbon-free power more cheaply and safely than today’s huge power plants

By Martin LaMonica

Big hopes for small nuclear

(Image: C. J. Burton/Corbis)

SPLITTING the atom has joined the start-up scene.

Green energy firms have long been popular ventures for entrepreneurs, but nuclear power has largely been ignored, thanks to the extreme cost, safety issues and the worries about nuclear proliferation that are usually associated with such an undertaking.

But a small group of nuclear scientists believe they can change things. By building new types of reactors, some of which reuse spent fuel rods from massive – and often ageing – power plants, they aim to commercialise cheaper, safer replacements to transform the industry.

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At the centre of conventional reactors are rods of uranium submerged in water. The rods contain about 5 per cent uranium-235, which readily sheds neutrons. As these neutrons fly into other uranium atoms, they knock loose more neutrons in a chain reaction that heats up the surrounding water. The steam this process creates is used to drive turbines to generate electricity.

These reactors make up the vast majority in service globally. The trouble is that, by the time the rods need replacing, only about one-twentieth of the radioactive material they contain has been used up, and so these power plants quickly accumulate highly radioactive waste. Enter the Waste Annihilating Molten Salt (WAMS) reactor, which is being developed by Transatomic Power in Cambridge, Massachusetts. The design calls for uranium and plutonium in used fuel rods to be dissolved in a tank of liquid lithium-fluoride salts. Heat from the radioactive elements builds within the salt, which can then be circulated out of the reactor’s core to a heat exchanger, where water is turned into steam to drive a turbine.

The design should mean that a disaster like the one in Fukushima, Japan, is out of the question&colon; in the case of a power outage, the unchecked heating of the molten salt would melt a plug below the core, draining the salt into a containment vessel that dissipates the heat. This would allow it to cool and solidify within a few hours, locking in any hazardous materials.

If all the nuclear waste currently in existence was reused in such reactors, they could supply the entire planet’s power needs for 72 years, carbon-free, claims Leslie Dewan, the company’s chief science officer.

If all the nuclear waste in existence was reused, it could meet the planet’s power needs for 72 years

WAMS is not the only game in town, though. With investment from Bill Gates, TerraPower of Bellevue, Washington, is designing a “travelling wave” reactor, which uses spent fuel to create a slowly expanding ring of fission in a reactor core that could sustain itself for decades.

The journey from the drawing board is long and expensive. Transatomic is currently looking to raise a “couple million dollars” to do materials testing, which will take about two years, says CEO Russ Wilcox. Then it would make a small demonstration plant, and finally a full-scale plant able to produce 500 megawatts. The whole process could take 15 to 20 years.

But if entrepreneurs don’t shoot for radical improvements to nuclear power, who will, says Jacob DeWitte, CEO of UPower Technologies in Boston. “Newer companies can help stimulate innovation in a traditional start-up sense,” he says. “Go hard, go fast, and try to make this a reality.”

Within five years, his firm hopes to commercialise what it calls a “nano-nuclear battery” that fits in a shipping container and generates 1 megawatt of power.